[hurd] 86/98: utils/rpctrace: fix output so that replies can be attributed to requests

[Samuel Thibault]

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sthibault pushed a commit to branch upstream
in repository hurd.

commit b372e439e05e336d5e52aa0ce69c799c15691932
Author: Justus Winter <address@hidden>
Date:   Fri Dec 13 15:25:22 2013 +0100

    utils/rpctrace: fix output so that replies can be attributed to requests
    
    Currently, it is impossible to properly attribute response messages to
    requests.  Even though rpctrace is single-threaded, its tracee may
    not.  Or there might be more than one tracee.  In any such case it is
    not guaranteed that the reply message we just processed is for the
    request we just printed.  Fix this by printing ellipsis with the port
    name, so that reply messages can be properly attributed:
    
    task129(pid3312)->mach_port_allocate (3) ...134
    task129(pid3312)->mach_port_deallocate (pn{  1}) ...160
    134... = 0 pn{ 30}
    160... = 0
    
    * utils/rpctrace.c (last_reply_port): New variable.
    (print_ellipsis): New function.
    (print_request_header): Optionally print ellipsis and update
    last_reply_port.
    (print_reply_header): Likewise.
---
 utils/rpctrace.c | 28 ++++++++++++++++++++++++++--
 1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/utils/rpctrace.c b/utils/rpctrace.c
index 0f68f44..d7ee203 100644
--- a/utils/rpctrace.c
+++ b/utils/rpctrace.c
@@ -1,7 +1,7 @@
 /* Trace RPCs sent to selected ports
 
-   Copyright (C) 1998, 1999, 2001, 2002, 2003, 2005, 2006, 2009, 2011
-   Free Software Foundation, Inc.
+   Copyright (C) 1998, 1999, 2001, 2002, 2003, 2005, 2006, 2009, 2011,
+   2013 Free Software Foundation, Inc.
 
    This file is part of the GNU Hurd.
 
@@ -1486,10 +1486,27 @@ static const char *const msg_types[] =
 };
 #endif
 
+/* We keep track of the last reply port used in a request we print to
+   ostream.  This way we can end incomplete requests with an ellipsis
+   and the name of the reply port.  When the reply finally arrives, we
+   start a new line with that port name and an ellipsis, making it
+   easy to match it to the associated request.  */
+static mach_port_t last_reply_port;
+
+/* Print an ellipsis if necessary.  */
+static void
+print_ellipsis (void)
+{
+  if (MACH_PORT_VALID (last_reply_port))
+    fprintf (ostream, " ...%u\n", (unsigned int) last_reply_port);
+}
+
 static void
 print_request_header (struct sender_info *receiver, mach_msg_header_t *msg)
 {
   const char *msgname = msgid_name (msg->msgh_id);
+  print_ellipsis ();
+  last_reply_port = msg->msgh_local_port;
 
   if (TRACED_INFO (receiver)->name != 0)
     fprintf (ostream, "%4s->", TRACED_INFO (receiver)->name);
@@ -1507,6 +1524,13 @@ static void
 print_reply_header (struct send_once_info *info, mig_reply_header_t *reply,
                    struct req_info *req)
 {
+  if (last_reply_port != info->pi.pi.port_right)
+    {
+      print_ellipsis ();
+      fprintf (ostream, "%u...", (unsigned int) info->pi.pi.port_right);
+    }
+  last_reply_port = MACH_PORT_NULL;
+
   /* We have printed a partial line for the request message,
      and now we have the corresponding reply.  */
   if (reply->Head.msgh_id == req->req_id + 100)

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